Abstract

EPR, microwave absorption, and dc magnetization measurements were made on single crystals of the form R2CuO4, which are the host compounds for the newly discovered series of electron cuprate superconductors. These measurements reveal two characteristic transition temperatures associated with a novel complex magnetic behavior, including weak ferromagnetism, two sharp peaks in the low field DC magnetization, an unusual anisotropy in the EPR resonance field for R = Gd, and two additional anisotropic microwave absorption modes. The higher characteristic transition temperature, at ≈270K, is attributed to AF ordering of the Cu moments, and the lower, at ≤20K, to a spontaneous canted spin reorientation. An understanding of this magnetic behavior is important in order to ascertain its relationship to possible mechanisms of high temperature superconductivity. © 1989.